OBJECTIVE： To investigate the effects of tirofiban combined with atorvastation before PCI on the miRNA expression of peripheral blood and vascular endothelial function in acute myocardial infarction （AMI） patients. METHODS： A total of 80 patients with AMI selected from our hospital as reaserch objects during Jan. 2015-Jun. 2016 were divided into control group and observation group according to random number table， with 40 cases in each group. Both groups received anticoagulant therapy. Control group was given Aspirin enteric-coated tablets 300 mg+Clopidogrel sulfate tablets 75 mg+ Atorvastatin calcium tablets 20 mg orally 30 min before PCI. Observation group was additionally given Tirofiban hydrochloride for injection with initial dose of 0.5 mg+0.9％ Sodium chloride injection 100 mL， iv， then adjusted to pump injection of 0.4 μg/（kg·min）， 30 min later adjusted to pump injection of 0.1 μg/（kg·min）， for consecutive 24 h. The levels of peripheral miRNA （miRNA-1， miRNA-133a， miRNA-208b， miRNA-499）， the levels of brachial artery diameter and vascular endothelial function indexes （vWF， ET-1， NO） were observed in 2 groups before medication and after PCI， and the occurrence of ADR was recorded. RESULTS： Before treatment， there was no statistical significance in above indexes between 2 groups （P＞0.05）. After treatment， miRNA expression， the levels of vWF and ET-1 were decreased significantly in 2 groups， and observation group was significantly lower than control group， with statistical significance （P＜0.05）. The brachial artery diameter and NO levels of 2 groups were increased significantly， and observation group was significantly greater or higher than control group， with statistical significance （P＜0.05）. No obvious ADR was found in 2 groups during treatment. CONCLUSIONS： For AMI， tirofiban combined with atorvastation before PCI can reduce miRNA expression， increase brachial artery diameter and protect vascular endothelial function with good safety.